Ads In Header Under Navigation

There is not enough information in your question.
Are you trying to use Widgets to display the content you refer to as ads?

There is also no way to understand how your site is messed up, which is another way to understand the issue.

This article discusses adding widgets up by/with the header:
https://www.realestatebloglab.com/twenty-ten-child-theme-add-widget-areas/